here are btw. some new ES9038Q2M-chinese-board pictures..
the board-layout seems to be changed to 1.04 and you can see how you can apply a input-selector switch to this..
(connected to JP2 and JP3; as described earlier and again on picture 3)
(basically you can do this too with another selektor on the other pins, so that u can change the different digital filter settings..(FIRs))
(Beware: according to some sources 0=Connection , X=Disjoin !!!)